Improvement of Water Barrier Property of Paperboard by Coating Application with Biodegradable Polymers

Abstract

Biopolymeric coatings were prepared and applied onto paperboard to improve its water barrier property. To prepare whey protein isolate (WPI)/cellulose-based films, WPI and glycerol were dissolved in water with glutaraldehyde (cross-linking agent) and cellulose xanthate. The solution was cast, dried, and insolubilized by entrapment of WPI in regenerated cellulose. Films were combined with beeswax (BW) into a bilayer coating system and then applied onto paperboard by heating compression. Another coating solution consisting of poly(vinyl butyral) (PVB)/zein was prepared by dissolving poly(vinyl alcohol) (PVA) and zein in 70% ethanol with glutaraldehyde and butyraldehyde (functionalization agent). The PVB/zein solution was applied onto paperboard after BW was sprayed. The structure of the PVB/zein-based coatings was analyzed by Fourier transform infrared spectroscopy (FTIR). The water vapor barrier property of coated paperboards was evaluated by water vapor transmission rate (WVTR) measurements. From the FTIR spectra, PVA functionalization after cross-linking and efficient acetalization into PVB were confirmed. WPI/cellulose and PVB/zein coating treatments improved the water barrier properties of paperboard by decreasing the WVTR by 77-78%. Although the BW coating was more efficient (decrease of WVTR by 89%), bilayer coatings composed of BW and polymer coatings had a stronger barrier effect with a decrease of WVTR to 92-95%, hence approaching commercial attributes required to ensure water vapor barrier in paperboard-based food containers (10 g/m(2).day). These results suggest that surface coating by biodegradable polymers may be utilized for the manufacture of paperboard containers in industrial applications.

Bio-Based Coatings for Paper Applications

“…The barrier properties can be further enhanced by cross-linking of the polymeric chains that makes the final material water-insoluble and suitable as a coating material for paper. The cross-links can be provided by adding a cross-linking agent like glutaraldehyde [65], or by initiating the formation of intermolecular disulphide bonds when the protein is heated to the denaturation temperature [66].…”

Reduced Water Permeability of Biodegradable PCL Nanocomposite Coated Paperboard Packaging

“…PCL is known for good water vapor properties 5,17 but PCL paperboard coating modified with Al 2 O 3 and SiO 2 nanoparticles is not widely investigated. The percentage results of the WVTR in relation to the control (K/0 -neat paperboard) are presented in Fig.…”

“…Many biopolymers are hygroscopic materials and can lose their barrier properties at high relative humidity (RH) due to water absorption 4 . PCL is a biopolymer with low water vapor transmission rate and has been used as a film on different materials 5 , Barrier properties can be additionally improved with the usage of different inorganic nanofillers for reinforcement, such as SiO 2 , Al 2 O 3 , ZnO, TiO 2 , etc. Besides the barrier properties, these inorganic nano-fillers can affect mechanical properties as well.…”

Effects of Cellulosic Base Sheet Pore Structure and Soybean Oil-Based Polymer Layer on Cellulosic Packaging Performance as a Barrier for Water and Water Vapor

“…Films formed by natural proteins and/or lipids such as whey protein, beeswax, and carnauba wax possess excellent barrier resistant properties to water and water vapor (Anker et al 2002;Lesar and Humar 2011). In one study, a bilayer coating composed of beeswax and fatty acid on paperboard significantly reduced the water vapor transmission rate (WVTR) by 92 to 95% (Jaejoon et al 2010).…”